A liquid crystal display device such as a liquid crystal TV receiver or a liquid crystal monitoring device is equipped with a backlight device that illuminates a liquid crystal panel from behind. This backlight device has a plurality of light sources arranged on the liquid crystal panel in the vertical direction and horizontal direction. Cold-cathode tubes or LEDs are used as the light sources.
It has hitherto been proposed for the liquid crystal display device to help the user easily view a display video of the liquid crystal display device by heightening the luminous intensity of the backlight device when the peripheral illuminance (ambient illuminance) is high but by lowering the luminous intensity of the backlight device when the peripheral illuminance is low (see e.g., Patent Documents 1 and 2). Specifically, the display luminance of the video is regulated by changing the luminous intensity of the backlight device through the change of the lighting time in the PWM control or the intermittent lighting control of the light sources of the backlight device.
Recently, as disclosed in Patent Document 2, the liquid crystal display device may execute an intermittent lighting process of each of the light sources that consists of a predetermined continuous light-on period and a predetermined continuous light-off period in one frame period. This secures a predetermined continuous light-off period (black insertion time) in one frame period to implement a pseudo impulse drive, thereby preventing motion blur in the display video as compared with a hold drive process in which the light sources remain on at all times. Furthermore, through the execution of a backlight scanning process of executing in sequence the intermittent lighting process of each of the light sources in conjunction with the action of writing an image signal to the liquid crystal panel, the time from writing of the image signal to turning on of the light sources can be evened over the entire screen, thereby enhancing the effect of improving motion blur in the display video.